DESCRIPTION: (Applicant's description) Development and testing of a protein differential display assay system, for proteomes of higher eukaryotes, using isotope-coded affinity tags (ICAT) and microcapillary liquid chromatography tandem mass spectrometry (uLC-MS/MS), is proposed. This system includes specific immunoaffinity capture of proteins during CAT analysis. Initial Phase I studies are proposed for development and optimization of phosphotyrosine specific protein differential display assay using a well characterized phosphotyrosine specific antibody and human carcinoma cells in culture. In Phase II, assays for other cell types and tissues will be developed. In addition, subtraction of high abundant and enrichment of low abundant proteins, in crude protein extracts, will be incorporated. Phase II studies also include use of novel CATs for comprehensive analysis of post-translational modifications.ln full development, this assay system provides for comprehensive analysis of the complex proteomes such as that of human. PROPOSED COMMERCIAL APPLICATION: Not available